BB life expectancy

[raindog]

In another thread, someone mentions having a bottom bracket replaced by their lbs before 500 miles. Is this normal?

In the old days, if you stripped a decent bb down once a year or so, packed it with grease and readjusted it, it would last more or less the life of the bike. And what's with this sealed unit thing anyway? They keep telling us the world's resources are getting a bit thin, so why this culture of chucking stuff away instead of being able to repair?

I've just changed the bb on my 'new' bike for the first time after a bit more than 7000 ks, and I was grumbling about it not lasting long. What sort of mileage do you guys get from these modern bb units?

 

[Alf]

20,000 on a Shimano UN72 still running freely. Changed a low-end Shimano sealed unit that came with the tandem after a few hundred, though, - felt very grotty.

In principle the old cups and loose balls should last a long time but you do have to keep adjusting them. or that was what I found anyway. Still got one in an old mountain bike but I don't think it will last much longer. The cups and the balls do wear. I am now a convert to the sealed units after initial skepticism.

Alf

 

[Theseus]

I have just had to replace an ISIS BB after 2.5years (about 10,000 miles). It was a fairly cheap one, but I replaced it with a Crank Bros one that is guarenteed for 5 years. Time will tell if it was worth the extra

 

[numbnuts]

I got 10,500 miles out of mine

 

[gf1959]

Peugeot road bike,17yrs old,same BB,no detectable wear. Hell of a lot of miles that's for sure in all weathers.

 

[Hont]

someone mentions having a bottom bracket replaced by their lbs before 500 miles. Is this normal?

Yes it's completely normal for some shops to suggest changing things way before they need to be.

 

[bad boy]

Well im pretty sure it was me Raindog was referring to and yes it was 470 miles exactly !!.

I have no bicycle maintenance experience so am at the mercy of the lbs. Im not saying he was having me over but the frustrating thing is that I just dont know. I am trying to learn and there are many things I can do now that I couldn't do 6 months ago but dont have that much time.

he did say it was a poor quality one that came with the bike

 

[tandemman]

I had a BB disintegrate completely after 300 miles on the tandem and it's replacement, an unbranded sealed unit costing 10 Euros, supplied and fitted, was still like new at 3500 miles I think, like most things you can get a good one or a bad one and you wont know until it fails.

 

[raindog]

like most things you can get a good one or a bad one and you wont know until it fails.

Yes, meant to say that there must be good and bad quality just like everything else. Anyway, looks like we're stuck with the system of "chuck it away and get another" whether we like it or not.

hi bad boy. Couldn't find that thread again. This place is pretty vast and I'm still trying to find my way around.

 

[Steve Austin]

I had to replace a Shimano XT Eternal BB unit after only 300ish miles. The left side had seized solid.
But then again i had been riding it through Kentish Clay, which does have a bad effect on Bearings

 

[xroads]

I have a Shimano BB-UN26 which has been used on two bikes and is still running smooth after 8000 miles, with zero maintenance. Pretty good for a BB which costs less than a tenner.

 

[Ticktockmy]

The sealed BB on my work treader is still going strong after 20 odd years, never been touched. I think BB failure is often down to riding style, if you try to use too high a gear in the wrong conditions, like standing on the peddles to ride up a hill, whereas a lower gear would allow you to remain seated, less pressure and strain on the BB, less strain on the seals. washing the bike with a pressure hose will for sure bugger up you BB.
My touring Bike, has done about 20,000 kms and no problems including some desert riding. Luck of the draw I think.

 

[lazyfatgit]

The BB on my Brompton is screaming after only a couple of hundred miles. will be looking for a warranty repair. rarely ridden in the rain, lives in the house.

Just had to replace one on the tourer, but thats about 8yr old, had couple of sets of tyres, now on it's 3rd chain. gets ridden in all weathers, on all sorts of roads and paths.

if the shimano lasts as well as the sugamo one which came out, i'll be dekighted.

 

[Mr Pig]

Possibly a lot depends on how hard you are on them. Do you sit and spin or stand and grunt? Are you light as a feather or fat as a..me! ;0) They're supposed to be sealed but if you ride in the rain enough I recon water will get in, or if you leave the bike outside. I fixed up someones bike a few months ago. It had hardly been used, literally a few miles, but had been left outside for months. The BB was shot, I think water had gotten into it.

 

[Paul_Smith SRCC]

20,000 on a Shimano UN72 still running freely....
Alf

A superb BB, a real shame we can’t get them!

Paul_Smith
www.corridori.co.uk